New Osteochondrosis Lesion Scoring System Developed

When it comes to scoring osteochondrosis lesions in young horses, a scale of one to five just won’t do. According to French researchers, increasing severity of lesions becomes so significant to the horse’s health and performance that a new, "weighted" scoring system is most appropriate for evaluating these growth-related bone and cartilage flaws.

"An osteochondral lesion that’s twice as big or twice as deep as another one isn't going to be just twice as severe—it's going to be exponentially severe with regard to that horse’s future athletic performance," said Jean-Marie Denoix, DVM, PhD, director of the Centre d'Imagerie et de Recherche sur les Affections Locomotrices Equines (CIRALE) in Goustranville (Normandy), France. "So we really needed a new scoring system that would reflect that kind of exponential difference."

Denoix's new system—which includes five weighted severity indexes (0, 1, 2, 4, and 8) for individual lesions—could also be used on all kinds of osteochondrosis lesions, a change from the current scoring systems. While there are a wide variety of osteochondral lesions which can occur on numerous places in the horse’s legs, most of the existing severity scoring systems are specific to individual kinds of lesions or locations, he said.

"Another limitation of (prior) scoring systems is that they are suitable for only one type of RF (radiographic finding), usually osteochondritis dissecans, or for only one joint or a particular part of a joint and cannot be applied to all joints that are usually routinely radiographed," added Johanna Lepeule, MS, PhD, researcher in the French National Institute for Agricultural Research.

The researchers tested the new grading scale on 392 young horses that were routinely screened for osteochondrosis as weanlings and again as yearlings, using a new field protocol involving 10 radiographic views.

Then, three equine veterinarians trained in the new scoring system reviewed the 7,270 resulting radiographs and score any visible lesions. The veterinarians then went back three months later and re-reviewed about a third of the radiographs. Finally, Lepeule and her colleagues compared the scores that the three veterinarians gave at the two different times.

The researchers found that the veterinarians were remarkably consistent in their severity scoring with the new system. In fact, when it involved severe lesions, the agreement among veterinarians and the repeatability of the scoring was excellent, Lepeule said. The only situation where the scoring was less consistent was in very mild lesions (scores of 0 or 1), particularly when they involved the front fetlocks or the knees.

But this was not especially surprising, she noted: "The demarcation between normal and pathological images is difficult to define. We therefore expected most disagreements would involve the lowest severity index (i.e., 1). Furthermore, 1 was the most frequent index observed for RFs (radiographic finding), which makes this index more exposed to disagreements."

The fact that the new scoring system is reliable is a significant benefit to equine health and management, she said. "The lack of standardized interpretation can result in conflicting diagnoses and recommendations between veterinarians, and in heterogeneous studies in research," she stated.

The new severity scoring system is now available to clinicians and can be viewed in Lepeule’s and Denoix’s full journal article. The study, " A reliable severity scoring system for radiographic findings in the limbs of young horses," was published in July in The Veterinary Journal.

About the Author

Christa Lesté-Lasserre is a freelance writer based in France. A native of Dallas, Texas, Lesté-Lasserre grew up riding Quarter Horses, Appaloosas, and Shetland Ponies. She holds a master’s degree in English, specializing in creative writing, from the University of Mississippi in Oxford and earned a bachelor's in journalism and creative writing with a minor in sciences from Baylor University in Waco, Texas. She currently keeps her two Trakehners at home near Paris. Follow Lesté-Lasserre on Twitter @christalestelas.

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